Bulb rectifier



March 6, 1928.

E. H. ROLLINSON BULB RECTIFIER Filed Ju1y28. 1922 2 ShootvSheot 1 March6, 1928. 7 1,661,579

E. H. ROLLINSON BULB RECTIFIER Filed July 28, 1922 2 shuts-shun 2 MWMlA/VE/YTOR A T ORIV Patented Mar. a, 1928.

UNITED STAT ES PATENT OFFICE EARL n. EoLLnisoiI, or LYONS rams,NEw'JEnsEY, assrouoza To 000mm HEWITT ELECTRIC COMPANY, OF EOBOKEN, NEWJERSEY, A CORPORATION or NEW JERSEY.

BULB REcTI'EIEE.

Application filed July 28, 1922. Serial No. 578,131.

In my prior application, Serial No. 461, 886, now Patent 1,591,185,filed April 16, 1921, I have described an improved arc rectifier with arectifier bulb, wherein the cathode is formed. from a closely I coiledfilament of tungsten, from which various leads are described as carryingA. C. to be rectified. The bulb is exhausted of air and usually filledwith some gas of the argon group. In the development and use of therectifier described in said application, the tungsten filament hasfrequently burned out. In experimenting with bulbs of this type, I havediscovered that the tungsten filament is not essential to the working ofthe rectifier; indeed I am able to operate the bulb after the filamenthas been completely ruptured equally as well as when the filament isintact. I am therefore able to use bulbs in which the filament hasbroken down by the system which I will fully describe in the followingspecification.

The object of my invention, therefore, is to construct a rectifiersystem wherein the cathode rods are unconnected and a high otentialspark between them serves as the initial ionizing agent, and thereafterthe operation of the system continues either with or without the highpotential spark.

A further object of my invention is to utilize exhausted rectifierbulbs, i. e. bulbs in which the tungsten filament is ruptured, whichunder the system which I have devised, last almost indefinitely, andwhen the cathode rods have been burned down to mere stubs, they may bereadily renewed by qpening up the bulb. Since the ionizlng o the gaswithin the bulb is produced by the spark between the cathode rods, Iprefer to protect them by covering their free ends with small carboncaps which have suflicient area to dissipate any destructive heat whichmay develop from the spark. A further objectpf my invention is toconstruct new bulbs with a supplemental or service cathode and utilize,what has been hitherto considered the Similar reference numerals referto like parts throughout the specification and draw- As set forth in myabove named prior application, the life of the rectifier bulb above,using the tungsten filament had theretofore been limited to about 800hours, but with the improvements set forth in the said application, thelife of the bulb is lengthened to about 1200 hours and in some casesconsiderably longer. By the improvements of my present invention, I amable to prolong the life of the bulb almost indefinitely, by

reason of the fact that the perishable part or element which hashitherto been considered as necessary to the rectification of A. C. isomitted and, the system of wirin slightly modified to correspond; also ahi frequency spark coil is introduced into t lde wiring system for thepurpose of starting its operation.

In Fig. 1, the transformer T, rectifier bulb 1, high frequency coil H.(l, reactance coil R. (1., storage battery B, ammeter A, and solenoidcircuit breaker 2 are of the usual type with the exception that in thebulb 1, the usual tungsten filament connecting the cathode leads 3, 4:is omitted and carbon caps 3, 4 are mounted thereon. The leads 3, 4together constitute a cathode element which is introduced into the tubeby a re-entrant stem :12, in which they are sealed in substantiallyparallel alignment with each other. Because of this parallel mounting,the spark distance between the leads remains approximately constant inlength, as they burn down in use. The bulb may be originally constructedwithout the filament, or bulbs in which such filament has broken downand which have hitherto been discarded as useless may be used. The transformer T has the usual secondary 5 and a tertiary winding 6; the firstbeing provided with a number of taps 7, 8 at each end for currentregulation, while the tertiary 6 is of small capacity usually about 10volts, and is utilized only as a starting means.

The wiring diagram may be described as follows: Starting from one of thetaps 7 the wire 9 leads to the reactance coil R. 0., thence wire 10leads to a terminal of the battery B, from the other terminal of whichthe wire 11 leads through the ammeter A to the bulb anode 12. From oneof the taps 8 at the other end of the secondary 5, the wire 13 leads tothe coil of the circuit breaker 2, from which the wire 14 leads to thecathode lead 3. If desired a small switch 15 may be located between thewires 13 and 14 in order to short circuit the circuit breaker 2. Thecarbon caps 3, 4' are mounted upon the free ends of the cathode rods 3,4 and by their large surface, serve to dissipate any destructive heatwhich might develop in the rods due to the spark.

The diagram for the starting or high frequency coil may be described asfollows The wire 16 leads from one end of the tertiary winding 6 to oneof the contacts 17 of the circuit breaker 2; from the other contact 18of which the wire 19 leads to and is connected with the armature side ofthe high frequency coil H. 0., from the primary of which the wire 20leads back to the other end of the transformer tertiary winding 6. Thesecondary of the high frequency coil C. is connected by the wire 21through the spark gap 22 to the cathode lead 3, and the wire 23 connectsthe other cathode lead 4 through a spark gap 24 with the wire 19.

A comparison of the diagram shown in Fig. 2 will show that it isidentical in all respects with that shown in Fig. 1 with the singleexception that the wire 25 connects the wires 11 and 21, through thespark gap 26; the diagram shown in Fig. 3 is identical in all respectswith Fig. 1 except that the cathode rods 3, 4 are connected solely intothe secondary circuit of the high tension coil, H. C. while a maincathode 27 is located directly between the rods or leads 3, 4 andconnected by wire 14 with the coil of the circuit breaker 2. Thisamounts structurally, only to the dividing of the cathode lead 3 intotwo elements one of which is connected to the transformer secondary andthe other to the high frequency coil secondary whereas in the otherdiagrams both of those secondaries are connected to a single cathodelead. v

The operation of the device is as follows: Upon closing the primary ofthe transformer T into the main or supply circuit, the high frequencycoil H. C. is immediately supplied with current coming from the tertiarywinding 6. The current therefrom taking the following path: by way ofthe wire 21, spark gap 22, cathode rod 3 across the cathode rod 4,thence by wire 23, spark gap 24 and wire 19 back to the high freuencycoil secondary. The high potential tius produced in the high frequencycoil, will reduce s arking at the gaps 22 and 24 and etween-t e cathoderods 3 and 4, which latter will result in ionizing the gas within thebulb 1. It may be stated at this point that the gaps 22 and 24 not onlyintensify the ionizing spark between the cathode rods 3 and 4, but servealso to insulate the high frequency coil H..C. from the transformersecondary 5. A peculiar hcnomenon develops as the spark is pro uccdacross the gap between the cathode rods 3 and 4. The spark first ap carsat the base of said leads, t at is, at tie points where they emerge fromthe glass support X, and when potential is supplied between the anode 12and the rods 3 or 4, the spark creeps up to the free ends of said rodswhere it remains. The spark thus produced, between the cathode leads orrods 3 and 4, ionizes the inert gas within the bulb and immediatelyelectrons begin to flow across between the anode 12 and the cathode 3,thereby establishin the rectifying circuit through the batte by way ofthe wires 9, 10, 11, 13 and 14. Thereafter the rectification roceedscontinuously until the battery B is c iarged.

It should be noted that the rectifyin circuit just described, includesthe smal circuit breaker 2; immediately upon the starting of therectifying current, this circuit breaker is opened at the oints 17, 18,thereby cutting out the high requency coil H. C. It may be thought, atfirst glance, that the opening of this circuit, eliminatin as it doesthe spark between the points of t e cathode rods 3 and 4 wouldimmediately sto the operation of the rectifying circuit. uch, however,is not the case for it is only necessary to start the rectification byproducing the spark across the cathode leads 3 and 4, whereupon thepoint of the cathode rod 3 is heated, by the bombardment of theelectrons flowing, and the rectif ing current, whereby the gas withinthe bulb becomes ionized; thereafter this bombardment of electronsbetween the point of the rod 3 and the anode 12 will be suflicient tomaintain the ionizing effect which is all that is necessary forcontinuous rectification.

If, for any reason, the rectifying current to the battery B should ceasetemporarily as by the opening of the circuit, the solenoid circuitbreaker 2 would be immediately deenergized, its core would drop, and thehi h frequency coil primary would at once ie thrown into circuit withthe tertia winding 6, when of course, the spark etween cathode rods 3and 4 would again be produced and rectification would again start uponthe reclosing of the open circuit. This renders the device automatic andself-starting so long as the supply circuit through the primary of thetransformer T is closed.

It is not essential that the high frequency coil H. C. be cut out ofoperation by the circuit breaker 2, since rectification would proceedjust the same if said circuit breaker produced between the cathode rods.

were omitted from the system and the wires 16 and 19 directly connected.I may accomplish such a result by closing the switch 15, thereby shortcircuiting the circuit breaker 2.

It will be noted that the diagram shown in Fig. 2 is identical with thatshown in Fig. 1 in all of its parts, with the single exception that thewire 25 connects the wires 21 and 11 with the spark gap 26 interposedtherein. By this slight modification, I am able to produce ionizationbetween the anode 12 and cathode 3 as well as between the cathode rods 3and 4.

With the rectifier as thus far described, I am able to use exhaustedbulbs in which the usual tungsten filament has broken down in use,inasmuch as I produce the ionizing efiect not by heat generated in anysuch filament or even in the cathode rods, but by the spark In thismanner, ionization is only initiated by the spark produced between saidrods, but such ionization is maintained by the are produced between thecathode 3 and anode 12, and this Whether or not the spark between thecathode rods 3 and 4 is maintained. The means described effectivelyproduces the spark be tween the cathode rods and after ionizationbegins, the maintenance of said spark is no longer essential. vSince theionization is continued by the arc spanning the gap be-.

tween the anode 12 and the cathode rod 3, this feature naturally leadsto the development of the form of bulb illustrated in Fig. 3. Here, thetwo rods 3 and 4 are connected up in circuit with the secondary of thehigh frequency coil and the spark is produced between said rods in themanner as above described. Interposed between the two rods 3 and 4, isthe service cathode rod 27, which is connected up by the wire 14 inexactly the same manner as above described in connection with Figs. 1and 2. The point of this cathode rod 27 is located directly'in the pathof the spark between the points of the rods 3 and 4 and when potentialis applied be tween the anode 12 and cathode rod 27, the

ionization produced causes current to flow to the service cathode rod27, whereas, in Figs. 1 and 2 the rod 3 serves the double purpose, thatis to say, as a cathode rod and also as a spark gap terminal. Afterrectification begins, the operation will be continuous, whether the highfrequency coil H. C. is kept in circuit by closing the switch 15 orautomatically cut out by the opening of said switch. In order to stillfurther intensify the spark between the rods 3 and 4:, I may insert acondenser C across the terminals of said cathode rods as shown in Figs.1 and 3.

l/Vhile it has been the custom to fill glass rectifier bulbs with argongas, yet I find that any of the inert gases such as neon gas ornitrlogen gas will serve the purpose equally wel In connection with Fig.2, I have described the wire 21 and the wire 11 as spanned by the wire25 and spark gap 26. With this form, a spark may be produced between theanode 12 and the electrode 4, as the initial ionizing agent.

The cathode caps 3 and 4 shown in Figs. 4 to 7 which are mounted uponthe free ends of the cathode rods 3, 4 are made of carbon and as aboveindicated they serve to dissipate the heat due to the are between saidcathodes and the anode 12. They also enable me to utilize othermaterials for cathode rods than the usual tungsten, as for example,molybdenum, tantalum, or some of the ot er less refractory of themetals. In Figs. 4: and 5, I have shown the caps as of a cup shape,while in Figs. 6 and 7 they are shown as fluted resembling a smallpinion. The form or shape however, is quite immaterial so long as asuitable radiating surface is afforded.

I claim:

A thermionic rectifier comprising a tube provided with a re-entrantstem, an anode and a cathode element, the latter comprising spaced,substantially parallel conductors mounted on said stem and designed toestablish an exciting are from one to the other.

EARL H. ROLLINSON.

